1. Field of the Invention
The present invention technology presented herein relates to a storage medium storing a virtual position determining program and, more particularly, to a storage medium storing a virtual position determining program for calculating the position of a virtual object in a virtual space based on the position of a target in the real space.
2. Description of the Background Art
In the prior art, Japanese Laid-Open Patent Publication No. 11-305935 (hereinafter “Patent Document 1”), for example, discloses a position detection system for taking an image of an infrared light source and analyzing the obtained image to determine a gunsight position.
As an example of a position detection system, Patent Document 1 discloses a shooter video game in which the player shoots targets by using, as a game controller, a gun-shaped controller provided with an image capturing device. Four infrared light sources are provided, as imaging targets, each at a corner of a cathode-ray tube, and an image thereof is taken by the image capturing device. The position on the cathode-ray tube being pointed at by the gun-shaped controller is detected based on the positions of the imaging targets on the obtained image. A virtual shooter game is played by using the position being pointed at by the gun-shaped controller as the gunsight position. As stated in Paragraph 21 of Patent Document 1, in a case where the distance between the image capturing device and the target (marker) can be changed freely, the gunsight position can be detected accurately if the image capturing device has a controllable zoom function and if the zoom function is controlled so that the marker on the obtained image always has an optimal size.
However, there is no such concept in the prior art that the position of the game controller, being an example of an input device, in the real space is used as a control input. In the position detection system disclosed in Patent Document 1, the position on the cathode-ray tube being pointed at by the gun-shaped controller is used as an input, but the pointed position only represents a position on the screen, not the position of the controller in the real space. While the distance between the image capturing device and the marker in the real space can be obtained, the distance is only used for making corrections. In other words, the distance is a sort of a value representing the position of the controller in the real space, but it is not used as a control input.
If the distance between the game controller and the imaging target is used as a control input, the range over which the player can move the game controller in the distance direction will be quite large. Therefore, the input range and the input variation will be significant, and it is difficult in the prior art to appropriately associate such a value with significant variations with the position of the controlled object in the virtual space. Moreover, where the player makes the control input vary depending on the situation, thereby varying the distance value, it is difficult to associate it with an appropriate virtual position. It is clear that similar problems will occur not only with the distance, which is a one-dimensional value, but also when detecting a three-dimensional position in the real space. With those problems as set forth above, there is no such concept in conventional control input methods that the position of the controller in the real space is used directly as a control input.